A toilet is the star of India's hit rom-com

Romance films don't usually revolve around a toilet.

But that's the angle in "Toilet: Ek Prem Katha" — or "Toilet: A Love Story," a Bollywood film starring superstar Akshay Kumar. And the box office has been flush with success. Since its release on Aug. 11, according to industry reports, the film has grossed $19.8 million at the box office worldwide, emerging as India's top film so far this year.

The plot is pretty straightforward: A young woman from a village marries a man from another village and moves in with his family, as is the custom.

She's horrified to learn that her husband's family doesn't have a toilet in their home.

The only way she can relieve herself is to join the women of the village, who rise at 4 a.m. every day in order to defecate in the fields while it's still dark (for privacy). And then they wait until sunset to use the fields again.

While they laugh and joke along the way, she feels humiliated and wants the privacy of a toilet.

But the villagers aren't on her side. Families in the village, including her in-laws, firmly believe that having a toilet in your home, where there's a kitchen and a prayer room, is unclean.

After arguing with her husband and delivering an ultimatum -- no toilet, no marriage -- she decides she has no choice but to leave the man she loves on the very first day of their marriage.

But he sets out to woo her back. And that means changing his mind about the need for toilets. Not only that, he sets out to change the community's toilet position as well.

This isn't just a made-up story for the movies. In a case of life imitating art, a week after the film released, Indian courts granted a divorce to a young woman on the grounds that her husband hadn't installed a toilet in their home, causing her much agony during their two-year marriage. In her complaint, filed in 2005, she said he had ignored her repeated requests for an indoor toilet.

Once the movie released, India's Twitterati responded to the film with its usual hilarity and there were plenty of toilet jokes.

Many felt the movie furthered the government's pro-toilet campaign. One reviewer called it actor "Akshay's paean" to Prime Minister Narendra Modi and his efforts to install more toilets in India:

And Twinkle Khanna, Bollywood actor, author and wife of leading man Akshay Khanna, tweeted:

Jokes aside, the movie lights up an issue that's never discussed on the silver screen --the challenges of creating the infrastructure for toilets in rural India and then persuading people to use them.

According to the government, 47 million toilets have been built in rural village communities and public spaces across India ever since Modi launched the Clean India Mission (Swatchh Bharat Abhiyan) initiative in October 2014 &mdahs; the anniversary of Gandhi's birthday. As a part of this mission, the government has promised to construct more public toilets and has launched the ODF (Open Defecation Free) campaign, an initiative to keep public spaces clean and free of excreta. A new government-sponsored app called "Find A Toilet" urged people to help locate, rate and review public toilets for factors such as cleanliness and hygiene.

But the challenges are immense, activists say.

While India's ambitious sanitation drive may have resulted in more toilets, there is no guarantee that people are actually using them, says Gaspard Appavou, a lawyer and social worker who handles human rights and environmental issues.

According to government records, 450 million Indians still defecate in the open. While many don't have access to a toilet, others could afford a toilet but don't want to change because of old prejudices and an ignorance of the health benefits.

The fact that the heroine of the film is pro-toilet reflects reality. Women are more receptive to setting up a toilet in their home than men are, says Appavou, who was a consultant for a UNICEF project that funded the installation of toilets in rural India. "Open defecation leaves women at higher risk to sexual violence. Using fields to defecate can expose them to snake and scorpion bite," he says. Men tend to use open spaces that are closer to their homes and aren't as worried about a lack of privacy.

This explains why the film has been a hit among rural women. It points up some of the problems that plague them -- especially the male indifference to how vulnerable women feel when they lack a toilet.

Bindeshwar Pathak, the founder of Sulabh International, which has set up 1.5 million eco-friendly community toilets in public spaces across 26 states in India, says the lack of toilets isn't just about sanitation and hygiene but directly linked to the progress of women. "I loved the family dynamics in the film," Pathak says. "The heroine makes it clear that she doesn't want to run and hide when she needs to relieve herself, that her dignity is so important to her, above all else. She urges the other women in the film to consider issues such as privacy and personal safety. I think it's a message that's empowering. It has condensed five decades of my life's work, taking it to those in need of change."

In an interview with the Hindustan Times, the film's director Shree Nayanan Singh suggests change on the issue is possible: "Films on social issues, till some time ago, were only limited to doing the rounds of film festivals, but the fact that we can now make a mainstream film about a taboo topic proves that [people are changing their views]."

Kamala Thiagarajan is a freelance journalist based in Madurai, South India. Her work has appeared in The International New York Times, BBC Travel and Forbes India. You can follow her @kamal_t